Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

The berries keep getting better. A U.S. Department of Agriculture scientist has found in them a compound that appears to be effective in lowering the bad forms of cholesterol, according to research made public Monday.

The compound, known as pterostilbene, appears to have many of the same cholesterol-fighting properties found in the antioxidant resveratrol, which is found in grapes and products like red wine, and led to wide reports that red wine was heart-healthy. Resveratrol also shows up in blueberries, but Agnes Rimando, a research chemist with the USDA's Agricultural Research Service, found that the pterostilbene in certain types of blueberries had a much more notable effect.

"Everybody thinks that's the wonderful compound in wine and grapes, but I was able to show there's another compound there thats equally chemopreventive," Rimando said. "I thought I'd look for other compounds in there and I found it."

Pterostilbene works in much the same manner as the popular anti-cholesterol drug ciprofibrate, sold commercially as Modalim. It binds to and activates a cell receptor known as PPAR-alpha, which research shows to be a key component in the body's ability to reducing cholesterol. Rimando reported her latest findings during this week's meeting of the American Chemical Society in Philadelphia.

Earlier this year she reported the presence of pterostilbene in blueberries, and two years ago, Rimando and her colleagues linked it to potential cancer-fighting properties, based on its ability to prevent cell destruction in mice.

Rimando, who works at a USDA lab in Oxford, Miss., found traces of pterostilbene in just two of 30 types of blueberries tested, deerberry and Rabbiteye blueberries, though she noted Rabbiteye is "a commercial blueberry" commonly found in U.S. produce aisles.

Extract may be best betDon't gorge yourself on berries just yet. Rimando cautioned it is not yet clear what dosage of pterostilbene is required for a positive effect. Plus, University of Scranton chemistry professor Joe Vinson pointed out, the antioxidant's greatest cholesterol-fighting value may be as an extract from blueberries, not the fruit themselves. Rimando tested only fresh blueberries and checked the various chemicals' efficacy in test tubes, not human subjects.

But Vinson added that pterostilbene's ability to impact PPAR-alpha receptors is significant because it can potentially reduce the amount of damaging low-density lipids, the type of cholesterol that causes artery blockage, and triglycerides, molecules used by the human body to store much of its fat.

"If you can get binding to this receptor, the molecule will have all kinds of good things happen -- lowering triglycerides, lowering cholesterol and raising the good cholesterol," Vinson said. "You can have it both ways with this receptor, and that's not an easy thing to do."

More research is needed to confirm pterostilbene's efficacy on human subjects. And the greatest eventual impact may be the development of blueberry-derived nutraceuticals, medicines formulated from naturally occuring plant substances. Such medicines could potentially avoid side effects found in ciprofibrate, including nausea and muscle pain.

Rimando sees her latest find as another good argument to eat more blueberries -- which, though they may not yet be proven to fight cholesterol, are still a pretty healthy snacking option.

"Grapes are still more popular than blueberries," she said, "but that's going to change."